To accurately measure the changes to the terrestrial biosphere on a global scale, Erle Ellis at the University of Maryland, Baltimore County, and coworkers integrated 300 years worth of information about human population with natural and human-induced changes in vegetation. They found that the biosphere switched from mostly wild to being dominated by human activity as recently as the beginning of the last century—the first demonstration of a worldwide effect.

The tool

Ellis integrated data “in a very elegant way,” says Faculty Member Rik Leemans. The researchers queried the land-use data with a series of “if-then” questions that let them classify the usage into more descriptive categories, which Ellis calls “anthromes”—such as wild, populated, and unused land within populated areas—and examined how these categories changed over three centuries.

The tamed

Ellis showed that of the unused land existent in 2000, about 40 percent was wild, while the remaining 60 percent were islands of unused habitat embedded within agricultural land or settlements. Ellis says that these areas, which have existed for only a few hundred years, represent “truly novel ecosystems.”

The future

“We can look at how humans have changed the biosphere in the past,” Ellis says, but the big question now is, “how do we want to change it in the future?” He is currently looking at how anthromes could be used to assess global changes in biodiversity and other long-term anthropogenic changes.